Can't find DLL entry point error w/ Dalton's GetTime example

[EricC]

I recently purchased the 2007 edition of Steve Dalton's Financial Applications Using Excel Add-In Development in C/C++ and am having difficulties implementing the "get time" call-a-DLL-from-a-VBA-function example in chapter 4.

What I did:

Built the DLL using Dalton's included code:

I copied the "GetTime VC6" folder from the software disc accompanying Dalton's book to a local directory. This folder includes a GetTime.cpp file containing a routine shown on page 100 of Dalton's book, a GetTime.def file that includes the following statement:

EXPORTS
Get_System_Time_C

The folder also includes a GetTime.dsp project file for Visual C++ 6.0.

I opened the GetTime.dsp using Microsoft Visual Studio C++ 2008 Express Edition, which converted the project into a 2008-compatible project.

I successfully built the project, which created the GetTime.dll and other files in the directory "C:\GetTimeExample\Debug\"

Opened Dalton's included Excel file and made file path modifications:

Next, I opened the GetTime.xls spreadsheet (included in the same Dalton CD) using Excel 2003.

I opened the VBA editor and entered in the full path of the DLL (C:\GetTimeExample\Debug\GetTime.dll") in the function declarations

The Problem:


Excel 2003 is not finding the DLL function. The spreadsheet gives me "#VALUE!" outputs in the "C run-time time function" and "C run-time clock function" cells.

While attempting to identify the problem, I created the following subroutine:

Sub Sub_Get_C_System_Time()

Call get_system_time_C(0) ' not necessary to pass trigger argument

End Sub

Then, when I attempt to run the subroutine, I get the following error:

Run-time error '453':

Can't find DLL entry point get_system_time_C in C:\GetTimeExample\Debug\GetTime.dll

Attempted But Failed Work-Arounds:

1) I prefaced an "extern "C"" command to the Get_System_Time_C function in GetTime.cpp and changed the corresponding GetTime.def entry to get_system_time_C=_get_system_time_C@4, but I got the same error.

2) In the Excel VBA window, I went to Tools/References/Browse and selected "C:\GetTimeExample\Debug\GetTime.dll". This returned the following error: "Can't add a reference to the specified file."

3) I added a "#include<windows.h>" statement to the cpp file (as shown on page 100 of the book). This made no difference.

I also searched Google for a solution, but was unable to find one.

Any suggestions?

Note:

I am experienced with Excel and fairly good with VBA. I did some C and C++ coding 20 years ago, in an old DOS environment. Although my C/C++ skills are very rusty, I want to write and link some C++ code into an Excel spreadsheet I developed (it desperately needs speed enhancements). I downloaded Microsoft's Visual Studio C++ 2008 Express Edition, but this compiler is very new to me.

 

[alain]

post all the code (and the XLS) here so we can get an idea

---------- Post added at 02:08 PM ---------- Previous post was at 02:07 PM ----------

BTW, there are various discussions on how to call C++ from Excel in QN. Just search for it.

 

[EricC]

Out of respect for Dalton's copyrights, I hope it is sufficient for me to post the relevant code pieces here:

From the GetTime.cpp file:

#include <time.h>
#define SECS_PER_DAY (24 * 60 * 60)
 
[SIZE=2][COLOR=#0000ff][SIZE=2][COLOR=#0000ff]long[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] current_system_time([/SIZE][SIZE=2][COLOR=#0000ff][SIZE=2][COLOR=#0000ff]void[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2])[/SIZE]
[SIZE=2]{[/SIZE]
[SIZE=2]time_t time_t_T;[/SIZE]
[SIZE=2][COLOR=#0000ff][SIZE=2][COLOR=#0000ff]struct[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] tm tm_T;[/SIZE]
[SIZE=2]time(&time_t_T);[/SIZE]
[SIZE=2]tm_T = *localtime(&time_t_T);[/SIZE]
[SIZE=2][COLOR=#0000ff][SIZE=2][COLOR=#0000ff]return[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] tm_T.tm_sec + 60 * (tm_T.tm_min + 60 * tm_T.tm_hour);[/SIZE]
[SIZE=2]}[/SIZE]
 
[SIZE=2][COLOR=#0000ff][SIZE=2][COLOR=#0000ff]double[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2][COLOR=#0000ff][SIZE=2][COLOR=#0000ff]__stdcall[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] Get_System_Time_C([/SIZE][SIZE=2][COLOR=#0000ff][SIZE=2][COLOR=#0000ff]long[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] trigger)[/SIZE]
[SIZE=2]{[/SIZE]
[SIZE=2][COLOR=#0000ff][SIZE=2][COLOR=#0000ff]return[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2] current_system_time() / ([/SIZE][SIZE=2][COLOR=#0000ff][SIZE=2][COLOR=#0000ff]double[/COLOR][/SIZE][/COLOR][/SIZE][SIZE=2])SECS_PER_DAY;[/SIZE]
[SIZE=2]}[/SIZE]

From the GetTime.def file:

[SIZE=2][SIZE=2]EXPORTS[/SIZE]
[SIZE=2]  Get_System_Time_C[/SIZE]
[/SIZE]

From the GetTime.xls spreadsheet:

Declare Function get_system_time_C Lib "C:\GetTimeExample\Debug\GetTime.dll" (ByVal trigger As Long) As Double
 
Option Explicit
 
Function Get_C_System_Time(trigger As Double) As Double
    Get_C_System_Time = get_system_time_C(0) ' not necessary to pass trigger argument
End Function

The spreadsheet includes a cell that has the following:

=Get_C_System_Time(0)

Which returns the "#VALUE!" error.

I also created the following subroutine in a VBA module:

Sub Sub_Get_C_System_Time()
    Call get_system_time_C(0) ' not necessary to pass trigger argument
End Sub

When I run that subroutine, I get the following error:

Run-time error '453':

Can't find DLL entry point get_system_time_C in C:\GetTimeExample\Debug\GetTime.dll

---------- Post added at 12:24 PM ---------- Previous post was at 11:23 AM ----------

I solved the problem.

The problem had to do with case sensitivity.

In Dalton's Excel spreadsheet, the "get_system_time_C" in the VBA function declaration needs to be changed to "Get_System_Time_C"

Then it works.

---------- Post added at 12:30 PM ---------- Previous post was at 12:24 PM ----------

I found and solved the problem -- it is an issue of case sensitivity

In the Excel spreadsheet on the Dalton disk, the VBA Function declaration is as follows:

Declare Function get_system_time_C Lib "GetTime.dll" (ByVal trigger As Long) As Double


It worked after I changed the declaration to:

Declare Function Get_System_Time_C Lib "GetTime.dll" (ByVal trigger As Long) As Double

I find it interesting that I wasn't able to find anything on the net noting the same problem -- even though scores of people, no doubt, try the same exercise after getting Dalton's book. Oh well, perhaps future users who run into this problem will find this thread.
​

Best regards,
Eric​

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